We investigate the magnetic sensitivity of molecular lines observed in sunspot umbrae and briefly discuss their major differences compared to atomic lines.

Ionization models for NGC 6210, 7009, 3242 and II 2003 have been constructed from optical and IUE spectroscopic data. The CIV 155 nm resonance line is predicted about ten times stronger than observed. Radiative transfer calculations of the CIV lines in a spherical nebula, assuming partial frequency redistribution, were made to investigate the effects of dust absorption and an additional depopulation of the upper level.

Although the subject of this meeting is triggered star formation in a turbulent interstellar medium, it remains unsettled what role magnetic fields play in the star formation process. This paper briefly reviews star formation model predictions for the ratio of mass to magnetic flux, describes how Zeeman observations can test these predictions, describes new results – an extensive OH Zeeman survey of dark cloud cores with the Arecibo telescope, and discusses the implications. Conclusions are that the new data support and extend the conclusions based on the older observational results – that observational data on magnetic fields in molecular clouds are consistent with the strong magnetic field model of star formation. In addition, the observational data on magnetic field strengths in the interstellar medium strongly suggest that molecular clouds must form primarily by accumulation of matter along field lines. Finally, a future observational project is described that could definitively test the ambipolar diffusion model for the formation of cores and hence of stars.

There is a long-standing mystery about the formation of the jets and lobes from AGN's. In the present paper, a “gravo-magnetodynamic” picture is proposed for the production of the jets and lobes from AGN's: The primordial large scale magnetic field, which is squeezed by the gravitational contraction of the material to the central object, serves in driving out the spinning jets in bipolar directions, and at the same time, serves as a drain extracting angular momentum of the disk material, enhancing the accretion and therefore enhancing the liberation of the gravitational energy at the center.

Young stars on their way to the ZAMS evolve in significantly different ways depending on their mass. While the theoretical and observational properties of low- and intermediate-mass stars are rather well understood and/or empirically tested, the situation for massive stars ([gsim ]10–15 M$_\odot$) is, to say the least, still elusive. On theoretical grounds, the PMS evolution of these objects should be extremely short, or nonexistent at all. Observationally, despite a great deal of effort, the simple (or bold) predictions of simplified models of massive star formation/evolution have proved more difficult to be checked. After a brief review of the theoretical expectations, I will highlight some critical test on young stars of various masses.

This conference is concerned with the very high resolution imaging of cosmic sources in many parts of the electromagnetic spectrum. Various techniques are now available and the equipment is often automated and highly sophisticated but the term ‘very high angular resolution’ is comparative. Many of the problems existed over forty years ago when the best resolving power was about half a degree and the two major radio ‘stars’ appeared to be point sources. Very high resolution imaging in those days was the struggle to reach one minute of arc and Hanbury Brown had set his sights on considerably better than one second of arc with the concept of the intensity interferometer. The dream was to achieve a resolving power comparable to that of optical telescopes.

Optical fibres have been used extensively within the Australia Telescope to carry IF data, LO reference, timing signals and computer communications. This paper discusses the various options considered in the design of a system which should assist similar projects in making the best use of optical fibres.

ESO has two telescope projects: the NTT (New Technology Telescope) with 3.5 m aperture and the VLT (Very Large Telescope) with 16 m equivalent aperture. The former is already in the engineering phase and should be completed in 1987; the latter is still in the study phase and will be described at this conference by our colleague, D. Enard.

This paper is concerned with the primary support system of the NTT. The basic principles and layout of this support have already been described in the literature 1,2,3).

The NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG) is the largest star formation survey of an H I selected sample. Since the selection is made without regard to optical morphology, it is not biased toward or against “interesting” types of galaxies; thus SINGG is an ideal sample for studying galaxy demographics. Of a sample of 90 extra-galactic sources observed in photometric conditions, all are detected in Hα. This indicates that dormant galaxies, those containing an appreciable ISM but no star formation, are at best rare. We have made first pass morphological surveys for starbursts, as judged by Hα surface brightness, and outflows as judged by extra-planar Hα. We find that about 15% of the sources contain starbursts, with little dependence on the neutral hydrogen mass MHI. Nearly one half of a sample ~ 35 edge-on galaxies show evidence for extra-planar Hα having a scale size of 0.5 Kpc or larger, while nearly one quarter have extra-planar Hα features 1.0 Kpc in size or larger. There is a hint that high MHI systems preferentially have displaced outflows (chimneys, or fountains) while central outflows (galactic winds) preferentially occur in low MHI systems. However, a larger sample (e.g. the full SINGG survey) is needed to confirm this trend.

An important effort has been recently made to detect spectroscopically galaxies at z ~ 6 and higher where the cosmic reionization is thought to occur. The drop of the fraction of Lyman Alpha Emitters (LAEs) at z>6 is currently interpreted as an effect of the increasing neutral hydrogen density.

We present preliminary results from the latest VLT/FORS2 programs, combined with ESO archival data, to perform a large census of z ~ 6 galaxies. We derive their physical properties as stellar mass and dust attenuation with an SED fitting tool including nebular emission which is of primeval importance because IRAC channels are strongly contaminated by emission lines at those redshifts. We take a special care to derive with precision the redshift of non LAEs to perform a comparison of their properties with the LAE population and derive as accurately as possible the fraction of LAEs. In particular, we compare the UV beta slope with the Lyα equivalent width which are known to correlate at lower redshift.

We also report the detection of few peculiar z ~ 6 galaxies with extremely blue UV β slope (~−3), which can be a signature of unusual stellar populations (e.g., very hot and massive stars).

As part of the Herschel Gould Belt Survey (HGBS), the Ophiuchus molecular cloud was imaged in the submillimeter range. Here, we summarize and briefly discuss the main results.

A global, monthly snow depth data set has been generated from weather satellite (Nimbus 7) observations using passive microwave remote-sensing techniques. In this paper we analyzed five years of data, 1980–1984, to compute the snow-load excitation of the annual wobble of the Earth's rotation axis. A uniform sea-level decrease has been assumed in order to conserve water mass. The result shows dominant seasonal cycles. The prograde component of the annual excitation is Ψ+ = (5.0 milliarcsec, −110*) and the retrograde component Ψ− = (5.0 milliarcsec, −31*). These computed values are compared with previous groundwater estimates, as well as the inferred values from ILS and LAGEOS polar motion measurements. The importance of accurate data is stressed and future plans proposed.

Six streams of dust were unexpectedly detected by the Ulysses dust detector while this spacecraft was approximately within one AU distance from Jupiter (Grün et al., 1993). Stream durations ranged from hours to days for individual streams. It was clear that the dust in these streams (or bursts), from their directionality of approach to the spacecraft and from the nearness of stream occurrences to Jupiter, emanated from the Jovian system.

Following the original report, Baguhl et al. (1994) later relaxed the criteria for differentiating true dust impacts from “noise pulses” and found almost triple the number of dust impacts in the six streams already found. They also found 5 more streams that, except for one stream, clearly emanated from the Jovian system. The criteria were relaxed in such a way as to not introduce “noise events” into the data.

21-cm line observations with the Westerbork Synthesis Radio Telescope of a dust and molecular filament at the boundary of the Draco Nebula (l≈ 91°, b≈ 38°) reveal a jet-like neutral hydrogen feature funneling through an outlet in the low velocity shock front at the interface between the Draco Nebula and the surrounding gas. The jet-like feature is apparently connected with a high velocity filament at VLSR = -180 km s-1. We suggest that the soft x-ray emission observed in the area is thermal bremsstrahlung produced by the deceleration of high velocity gas in galactic gas.

We estimate distances to the spherical planetary nebula Abell 39 and the bipolar planetary nebula NGC 7027 by interpolating from a wide grid of photoionization models using the 3-D code, MOCASSIN. We find preliminary distances of 1.5 kpc and 0.9 kpc respectively, with uncertainties of about 30%.

We report on the activities preparing long duration stratospheric flights, suitable for CMB (Cosmic Microwave Background) measurements, in the Arctic region. We focus on pathfinder flights, and on two forthcoming experiments to be flown from Longyearbyen (Svalbard islands): the OLIMPO Sunyaev-Zeldovich spectrometer, and the Large-Scale Polarization Explorer (LSPE).

Huygens is an entry probe designed to descend under parachute through the atmosphere of Titan, Saturn’s largest moon. The Huygens Probe is provided by the European Space Agency (ESA) for the Cassini/Huygens mission to Saturn and Titan. The Huygens mission will be conducted on the 3rd Orbit around Saturn. The probe will be released around December 25, 2004 for entry in Titan on January 14, 2005. This paper provided an overview of the Huygens mission. The status of the probe and of the mission was reviewed, and opportunities for Titan observations by the Orbiter during the first two orbits were discussed. The Cassini/Huygens mission is a joint undertaking by NASA and ESA, with ASI as a partner via a bilateral agreement with NASA.

Improved observing and data analysis strategies have initiated a considerable expansion of the empirical knowledge about the pulsations of OB stars. Possible correlations between physical parameters and associated pulsation characteristics are becoming more clearly perceivable. This starts to include the asteroseismologically fundamental areas of g-modes and rapid rotation. The β Cephei instability strip continues to be the only locus where radial pulsations occur (but apparently not in all stars located in that strip). Except for spectral types B8/B9 near the main sequence, where pulsations are hardly detected even at low amplitudes, any major group of stars in the Galaxy that are obviously not candidate pulsators still remains to be identified. However, the incidence and amplitudes of OB star pulsations decrease steeply with metallicity. The behaviour of high-luminosity stars is less often dominated by very few modes. In broad-lined stars the moving-bump phenomenon is more common than low-order line-profile variability. But its relation to nonradial pulsation is not clear. The beating of low-ℓ nonradial pulsation modes that have identical angular mode indices may be the clockwork of the outbursts of at least some Be stars. The physics of this episodic mass loss process remains to be identified.

Amateur astronomers have a vast store of talent and expertise in making astronomical observations. When carefully channelled, their enthusiasm coupled with these characteristics can lead to the acquisition of large volumes of high-quality astronomical data. The Amateur Observation Network of the International Halley Watch (IHW) was organized to encourage comet observations by amateurs, standardize techniques whenever possible, and then collect and archive these observations for use by the astronomical community in the near and distant future as part of the whole IHW archive. The lessons learned from this experience will be useful to organizers who plan observation campaigns involving amateur astronomers in the future.

We review the nearby debris disk structures revealed by multi-wavelength images from Spitzer and Herschel, and complemented with detailed spectral energy distribution modeling. Similar to the definition of habitable zones around stars, debris disk structures should be identified and characterized in terms of dust temperatures rather than physical distances so that the heating power of different spectral type of stars is taken into account and common features in disks can be discussed and compared directly. Common features, such as warm (~150 K) dust belts near the water-ice line and cold (~50 K) Kuiper-belt analogs, give rise to our emerging understanding of the levels of order in debris disk structures and illuminate various processes about the formation and evolution of exoplanetary systems. In light of the disk structures in the debris disk twins (Vega and Fomalhaut), and the current limits on the masses of planetary objects, we suggest that the large gap between the warm and cold dust belts is the best signpost for multiple (low-mass) planets beyond the water-ice line.